The mechanical machines, e.g. engineering machines or agriculture machines in the art are designed to perform various tasks, wherein different work tools are mounted by unified or standard work tool clamping devices. For these multi-functionality machines, usually corresponding work tools have to be changed during switching among different tasks. For this, a corresponding quick change device of a work tool is provided.
Generally speaking, current quick change device of a work tool is equipped with an alarming horn, which sounds when a work tool clamping device is in a disengaged position. The alarming horn is used to remind an operator of the fact that the work tool clamping device is in the disengaged position and that the work tool is not connected or fastened. However, if the alarming horn fails to work due to failure of an electric circuit thereof, the operator will not be informed that the work tool clamping device is in the disengaged position. In this case, the operator may perform the operation when the work tool clamping device is not engaged or the work tool is not fastened, because he/she is not aware of the fact that the work tool clamping device in the disengaged position. The work tool therefore may come loose and fall down, even resulting in safety accident.